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See detailDo changes in atmospheric CO2 concentration affect aphid alarm signaling?
Boullis, Antoine ULg; Appeldoorn, Claire; Oostrom, Marjolein et al

Conference (2015, November 06)

The effects of global atmospheric changes on vegetation and associated insect populations are increasingly studied, but how these gases affect the interactions between herbivore insects and their natural ... [more ▼]

The effects of global atmospheric changes on vegetation and associated insect populations are increasingly studied, but how these gases affect the interactions between herbivore insects and their natural enemies is less clear. As the efficacy of natural enemies is governed largely by behavioral mechanisms, changes in the behavior of insect prey defenses can change the dynamics of insect populations. The impact of increases in atmospheric carbon dioxide (CO2) concentrations on aphid population dynamic is well documented. However, few publications about their chemical ecology are reported. Aphids are using many chemical signals to communicate with each other or with their environment. For example aphids produce an alarm pheromone to signal the presence of a natural enemy in the colony. For our experiments, aphids Acyrthosiphon pisum (Harris) were reared on Vicia faba L. in home-made Plexiglas® chambers, allowing us to control the CO2 concentration, temperature and humidity. Aphids were reared under both ambient (aCO2 ≈ 400 ppm) and elevated (eCO2 ≈ 800 ppm) CO2 concentration for several generations. Here we quantified the emission of (E)-β-Farnesene (EβF - main compound of alarm pheromone) released by predated aphids reared under ambient or elevated CO2 concentration, with two different methods: a real-time analysis, and the total amount analysis. The EβF content of whole aphid bodies was also analyzed, as well as the escape behavior of aphid colony according to the growing conditions of aphid populations. These results will be discussed in terms of biological control in future climate. [less ▲]

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See detailComposite dark matter and direct-search experiments
Wallemacq, Quentin ULg

in International Journal of Modern Physics D : Gravitation, Astrophysics & Cosmology (2015), 24

The results of the direct searches for dark matter are reinterpreted in the framework of composite dark matter, i.e. dark matter particles that form neutral bound states, generically called “dark atoms” ... [more ▼]

The results of the direct searches for dark matter are reinterpreted in the framework of composite dark matter, i.e. dark matter particles that form neutral bound states, generically called “dark atoms”. Two different scenarios are presented: milli-interacting dark matter and dark anti-atoms. In both of them, dark matter interacts sufficiently strongly with terrestrial matter to be stopped in it before reaching underground detec- tors, which are typically located at a depth of 1 km. As they drift towards the center of the earth because of gravity, these thermal dark atoms are radiatively captured by the atoms of the active medium of underground detectors, which causes the emission of photons that produce the signals through their interac- tions with the electrons of the medium. This provides a way of reinterpreting the results in terms of electron recoils instead of nuclear recoils. The two models involve milli-charges and are able to reconcile the most contradictory experiments. We determine, for each model, the regions in the parameter space that reproduce the experiments with positive results in con- sistency with the constraints of the experiments with negative results. [less ▲]

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See detailFE2 approach for the modelling of coupled hydro-mechanical behaviour of partially saturated coalbeds
Bertrand, François ULg

Diverse speeche and writing (2015)

Présentation de projet de thèse au comité FRIA

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See detailCHANGEMENT CLIMATIQUE: CAUSES ET CONSEQUENCES (2015) - ANALYSE HOLISTIQUE -
Ozer, Pierre ULg

Scientific conference (2015, November 06)

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See detailAnalyse multifractale de la divergence de séries d'ondelettes
Esser, Céline ULg

Scientific conference (2015, November 06)

Dans cet exposé, nous étudions la divergence ponctuelle de séries d'ondelettes dans un espace de Besov. Nous obtenons une borne supérieure pour la dimension de Hausdorff de l'ensemble des points ayant un ... [more ▼]

Dans cet exposé, nous étudions la divergence ponctuelle de séries d'ondelettes dans un espace de Besov. Nous obtenons une borne supérieure pour la dimension de Hausdorff de l'ensemble des points ayant un taux de divergence donné, et nous montrons que cette borne est optimale en utilisant les notions de résidualité et de prévalence. Il s'agit d'un travail en collaboration avec S. Jaffard. [less ▲]

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See detailImpact of Regiella insecticola infection on EBF production in Acyrthosiphon pisum Harris
Bauwens, Julien ULg; Mazzucchelli, Gabriel ULg; De Pauw, Edwin ULg et al

Conference (2015, November 06)

Symbionts of aphids influence their host from many points of view. We investigate the potential influence of bacterial symbionts on the production and emission of the aphid alarm pheromone, E-β-franesene ... [more ▼]

Symbionts of aphids influence their host from many points of view. We investigate the potential influence of bacterial symbionts on the production and emission of the aphid alarm pheromone, E-β-franesene. Some trends could be observed in the total EβF production. Particularly, aphid strains infected by Buchnera only seemed to produce less alarm pheromone. By contrast, the presence of Regiella insecticola seemed to increase EβF production. Mevalonate pathway was investigated by RT-qPCR. This analysis showed a slightly lower transcription level o mIPPS in Regiella-infected strains. This enzyme is involved in the last step of EβF production. By contrast, two enzymes involved respectively in the linkage and release of farnesyl moeities on proteins c-terminal ends. Escape tests were conducted to assay if these results were traduced by differential behavior in front of a predator. Preliminary results showed significantly higher dropping behavior for Regiella-infected strains. [less ▲]

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See detailL'Automobile dans le comic strip : un passage à toute vitesse
Crucifix, Benoît ULg

Article for general public (2015)

Né au tournant du XXe siècle, au cœur de la modernité, le comic strip s’est tout de suite approprié ces rapides changements apportés par la modernisation, son industrialisation et sa croissance urbaine ... [more ▼]

Né au tournant du XXe siècle, au cœur de la modernité, le comic strip s’est tout de suite approprié ces rapides changements apportés par la modernisation, son industrialisation et sa croissance urbaine, son éventail de nouvelles technologies, spectacles et attractions. Son « langage » est d’ailleurs intimement nourri de ces changements : comme le suggère Thierry Smolderen dans Naissances de la bande dessinée, la bande dessinée s’est développée dans le laboratoire de l’illustration humoristique et de sa dynamique « polygraphique », pris dans une vibrante dynamique culturelle de dialogue entre différents médias. Tout comme la chronophotographie pour le phonographe, les transformations technologiques et urbaines qui ont marqué le tournant du XXe siècle ont offert un terrain particulièrement fertile aux illustrateurs et cartoonists, qui s’en saisissent allègrement. Ce que le comic strip donne à voir c’est donc bien ce nouvel environnement urbain que navigue ses lecteurs. Cela en va de même pour les moyens de locomotion et le trafic urbain, un sujet-clé cultivé par les cartoonistes : métro, tramways, zeppelins, calèches, tout y passait. Mais ce rapport à la modernité, c’est aussi un lien à une culture de l’accélération et de la vitesse mécanisée, concomitant avec le boom de la bicyclette et de l’automobile. Il n’est donc pas étonnant que les automobiles, qui se sont développées au même moment que le comic strip, y soit richement figurées, prenant la forme d’une véritable attraction. [less ▲]

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See detailLa liberté religieuse sur les lieux de travail
Kéfer, Fabienne ULg

Scientific conference (2015, November 06)

This conference explores the way in which Belgian law deals with situations where labour law engages with the right to freedom of religion and belief and the right not to be discriminated on grounds of ... [more ▼]

This conference explores the way in which Belgian law deals with situations where labour law engages with the right to freedom of religion and belief and the right not to be discriminated on grounds of religion. It starts with the Belgian regime of religious freedom, protection against discrimination and valid reasons for termination of employment. It then considers specific areas of those regimes in Belgian labour relations, such as the work schedule accommodation, the refusal to perform work, clothing and religious symbols in the workplace, and the work in an ethos organization. It relates mainly to Belgian case law but also to the case law of the European courts [less ▲]

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See detailReinventing paternalism. The micropolitics of work in the mining companies of Central Africa
Rubbers, Benjamin ULg

Scientific conference (2015, November 06)

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See detailBiomakers of osteoarthritis
Henrotin, Yves ULg

Conference (2015, November 05)

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See detailRôle du gorille des plaines de l’Ouest (Gorilla gorilla gorilla) dans la régénération des forêts denses humides et interaction avec l’exploitation sélective de bois d’oeuvre
Haurez, Barbara ULg

Doctoral thesis (2015)

According to the IUCN, the western lowland gorilla (Gorilla gorilla gorilla Savage & Wyman) is a critically endangered species. This species would play an important role in tropical forest dynamics ... [more ▼]

According to the IUCN, the western lowland gorilla (Gorilla gorilla gorilla Savage & Wyman) is a critically endangered species. This species would play an important role in tropical forest dynamics. Indeed, its highly frugivorous diet and its large body mass would result in the implication of gorilla in the seed dispersal of many plant species. Moreover, by building its nest sites in open canopy forest, it would deposit the majority of seeds in habitats displaying potentially suitable light condition for their germination and for the subsequent seedling development. However, given the expansion of timber exploitation in Central Africa, ecological services dispensed by gorilla could be threatened. The objective of this thesis is to characterize the impacts of timber exploitation on gorilla populations and the role of these populations in forest regeneration after logging. The results demonstrate that a viable population of gorilla may be maintained in selectively logged forests (< 2 trees ha-1). Indeed, although gorillas tend to flee areas during timber exploitation activities, their density in logged forest reaches its initial value, or even a higher level, within one year after the end of logging. The preferential selection of open canopy forest areas for nesting was verified, before and after logging. The deposition of seeds in habitats providing favorable light conditions is therefore confirmed, even though the preference for tree fall gaps and forest skid trails was not observed in the course of the monitoring period (one year after logging). The seeds of 59 plant species were found in gorilla feces collected over a period of 20 months. A quarter of these species presented an economically value because of their use as timber or non-timber forest products. The analyzed fecal units contained between one and six different seed species, and on average 81.0 ± 107.8 intact seeds (0-566). Depending on the species considered, germination success varied from 0 to 100 %, with an average of 46 ± 36 %. The gorilla is the main disperser of a timber species, Dacryodes normandii. Over the fructification period, the gorilla consumed fruits of this species in 87.8 % of its visits (of an average length of 85 ± 89 min.). The impact of gut passage was evaluated for two tree species, Santiria trimera and Chrysophyllum lacourtianum. These species displayed higher germination successes after gorilla ingestion because of both pulp suppression and seed coat scarification. In addition, a positive effect of fecal matrix on seedling development was observed for three studied species, S. trimera, C. lacourtianum and Plagiostyles africana. Finally, the development of seedlings is favored in nesting sites, the most frequent seed deposition sites. Two studied species, S. trimera and Dacryodes normandii displayed a growth between two and ten times faster in nest sites than in closed canopy forest. Therefore, gorilla is implicated in directed seed dispersal. Consequently, when poaching is absent, western lowland gorilla populations seem to be resilient to selective logging and they play a critical role in the seed dispersal process, both quantitatively and qualitatively, in logged forests. Some recommendations to improve the management of logged forest that host gorilla populations were proposed in order to favor their preservation within logging concessions. In particular, the generalization of reduced impact logging practices is advisable. [less ▲]

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See detailNew features in SAFIR® 2016
Franssen, Jean-Marc ULg; Gernay, Thomas ULg

Scientific conference (2015, November 05)

This presentation gives an overview of the new features implemented in the version 2016 of SAFIR, the finite element software dedicated to the analysis of buildings in fire.

Detailed reference viewed: 28 (3 ULg)
See detailGame studies in french speaking area
Hurel, Pierre-Yves ULg

Conference (2015, November 05)

Dans cette communication, j'ai présenté le champ des "game studies" à mon laboratoire d'accueil, le GAP, au sein duquel j'ai effectué un séjour de recherche d'octobre à décembre 2015. J'ai présenté les ... [more ▼]

Dans cette communication, j'ai présenté le champ des "game studies" à mon laboratoire d'accueil, le GAP, au sein duquel j'ai effectué un séjour de recherche d'octobre à décembre 2015. J'ai présenté les principales spécificités du champ francophone (tel quel le recours à Henriot), les institutions structurant le milieu (OMNSH, LabJMV, etc.) et quelques travaux récents et reconnus. [less ▲]

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See detailPost-scriptum à La Misère du monde 25 ans après : Bourdieu, le peuple et son sociocide
Cormann, Grégory ULg

Scientific conference (2015, November 05)

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See detailApplications de la terre crue en construction
Grigoletto, Sophie ULg; Paul, Julien; Lebeau, Frédéric ULg et al

Conference (2015, November 05)

L’utilisation de l’argile en construction permet d’atteindre des propriétés spécifiques en termes de résistance mécanique et d’inertie thermique. Les recherches menées à l’Université de Liège, en ... [more ▼]

L’utilisation de l’argile en construction permet d’atteindre des propriétés spécifiques en termes de résistance mécanique et d’inertie thermique. Les recherches menées à l’Université de Liège, en collaboration avec l’entreprise MOBIC, ont permis de développer des produits permettant l’amélioration de l’inertie thermique de panneaux à ossature bois. L’effet de l’apport de la couche d’inertie au sein des constructions à ossature bois a été quantifié expérimentalement par l’instrumentation de modules jumeaux de 20m². Cet effet sur le confort thermique a également été modélisé par des simulations thermiques en vue de quantifier les bénéfices sur les surchauffes en été, les réductions des consommations énergétiques en hiver pour divers scénarii au moyen d’un programme de simulation dynamique des échanges thermiques et des bilans d’énergie au sein de bâtiments [less ▲]

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See detailApplications de l'argile crue en construction
Grigoletto, Sophie ULg; paul, Julien

Conference (2015, November 05)

L’utilisation de l’argile en construction permet d’atteindre des propriétés spécifiques en termes de résistance mécanique et d’inertie thermique. Les recherches menées à l’Université de Liège, en ... [more ▼]

L’utilisation de l’argile en construction permet d’atteindre des propriétés spécifiques en termes de résistance mécanique et d’inertie thermique. Les recherches menées à l’Université de Liège, en collaboration avec l’entreprise MOBIC, ont permis de développer des produits permettant l’amélioration de l’inertie thermique de panneaux à ossature bois. L’effet de l’apport de la couche d’inertie au sein des constructions à ossature bois a été quantifié expérimentalement par l’instrumentation de modules jumeaux de 20m². Cet effet sur le confort thermique a également été modélisé par des simulations thermiques en vue de quantifier les bénéfices sur les surchauffes en été, les réductions des consommations énergétiques en hiver pour divers scénarii au moyen d’un programme de simulation dynamique des échanges thermiques et des bilans d’énergie au sein de bâtiments [less ▲]

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See detailSeals as toxicological models to study the transfer of contaminants in the food chain
Das, Krishna ULg

Scientific conference (2015, November 05)

Detailed reference viewed: 13 (3 ULg)